BB Curve :: Using Wi-Fi To Connect To Email, Web Browser?

Just recently I bought a Blackberry Curve 8900 with tmobile. Now here is the thing, I dont have a data plan of any kind with tmobile. So when I bought the phone I insterted my phone and booted it up. Checked with my seller to make sure it made a phone call.it did. So I knew for sure my SIM card was working just fine.heres where it gets weird.

When I got home, the first thing I did was connect to my wireless network.. using Wi-Fi.. obviously. And from there I went to the Setup Wizard and went through each step. When I got to the Email portion, It gave me two options, I dont remember both but one of them was "set up email through blackberry enterprise server".. or something like that. I was aware that I didnt have a data plan, so I clicked the second option. I went through the process and had EMAIL... through WIFI. I even sent my self email messages to make sure it was working and have proof that i recieved email and sent emaily to myself and others!!! without a data plan!!!

This is what i expected.. i didnt know that this wasnt supposed to happen? and that blackberrys customers were only able to get email if they had a blackberry data plan?Well, naturally i figured everything else would work on a wif connection.. like the iphone. Even though you dont have the 3G data plan one can still access email, web, and aps. So anways, all the apps communicated with the wifi network and my web browser viewed pages on a wireless network.

Then my myfaves dissapeard and gave a java encoding script error or something. So what do i do? i call tmobile and spend hours troubleshooting. Eventually i am able to restore or update my OS with a PC and get my mfaves back. But now my ap world ap wont start and tells me that i need a data plan.. next its my web browser that tells me the same thing, as well as facebook. I am like what is going on?!. AND then when I try to set up email. there is only one option.and thats "setup email through a blackberry enterprise server"..So my question is.if you took the time to read this.why in the world did everything stop working with wi fi and out of nowhere asked me to use a blackberry data service plan?